An AMOLED (Active Matrix Organic Light Emitting Diode) display is widely used because of its wide viewing angle, high color contrast, fast response speed, and low cost. The reason why AMOLED is capable of emitting light is that it is driven by a current generated by a driving Thin Film Transistor (TFT) when being saturated. No matter which one of an LTPS (Low Temperature PolySilicon) process or an oxide process is used, due to the non-uniformity of the process, the backplane of a thin film transistor has a poor uniformity in terms of the threshold voltage (Vth) for the driving Thin Film Transistor at different positions during the process, and Vth also drifts, both of which are threats to the consistency for a current-driven device. Because different threshold voltages may lead to different driving current when a same gray-scale voltage is input, the resulting currents are not consistent. A conventional AMOLET driving circuit comprises two thin film transistors and one storage capacitor (or simply, 2T1C), and such a circuit always has a poor uniformity in luminance. FIG. 1 shows a block diagram of a 2T1C circuit, and FIG. 2 shows operation timing diagram of this 2T1C circuit.